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Subject[PATCH v3 2/3] pwm: stm32-lp: Add power management support
Date
Add suspend/resume PM sleep ops. When going to low power, enforce the PWM
channel isn't active. Let the PWM consumers disable it during their own
suspend sequence. Only perform a check here, and handle the pinctrl states.
See [1].
[1] https://lkml.org/lkml/2019/2/5/770

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
Changes in v2:
- Don't disable PWM channel: let the PWM user disable it. Refuse to
suspend in case it's been left enabled.
- Drop the ifdefs, use __maybe_unused instead.
---
drivers/pwm/pwm-stm32-lp.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)

diff --git a/drivers/pwm/pwm-stm32-lp.c b/drivers/pwm/pwm-stm32-lp.c
index 0059b24c..2211a64 100644
--- a/drivers/pwm/pwm-stm32-lp.c
+++ b/drivers/pwm/pwm-stm32-lp.c
@@ -13,6 +13,7 @@
#include <linux/mfd/stm32-lptimer.h>
#include <linux/module.h>
#include <linux/of.h>
+#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>

@@ -223,6 +224,29 @@ static int stm32_pwm_lp_remove(struct platform_device *pdev)
return pwmchip_remove(&priv->chip);
}

+static int __maybe_unused stm32_pwm_lp_suspend(struct device *dev)
+{
+ struct stm32_pwm_lp *priv = dev_get_drvdata(dev);
+ struct pwm_state state;
+
+ pwm_get_state(&priv->chip.pwms[0], &state);
+ if (state.enabled) {
+ dev_err(dev, "The consumer didn't stop us (%s)\n",
+ priv->chip.pwms[0].label);
+ return -EBUSY;
+ }
+
+ return pinctrl_pm_select_sleep_state(dev);
+}
+
+static int __maybe_unused stm32_pwm_lp_resume(struct device *dev)
+{
+ return pinctrl_pm_select_default_state(dev);
+}
+
+static SIMPLE_DEV_PM_OPS(stm32_pwm_lp_pm_ops, stm32_pwm_lp_suspend,
+ stm32_pwm_lp_resume);
+
static const struct of_device_id stm32_pwm_lp_of_match[] = {
{ .compatible = "st,stm32-pwm-lp", },
{},
@@ -235,6 +259,7 @@ static int stm32_pwm_lp_remove(struct platform_device *pdev)
.driver = {
.name = "stm32-pwm-lp",
.of_match_table = of_match_ptr(stm32_pwm_lp_of_match),
+ .pm = &stm32_pwm_lp_pm_ops,
},
};
module_platform_driver(stm32_pwm_lp_driver);
--
1.9.1
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